Well the interesting thing is there were so many influxes of European colonists that you could go a lot of different ways.

Did Spanish wizards decide to conquer their way across the Americas like their Muggle counterparts? Did the French find ways to ally with the Native Americans? Would a whole lot of French and British wizards even come to Wizarding USA? What societal pressures in Europe would drive them there?

The Vikings visited the Americas well before the Spaniards did, would that reflect in modern day culture?

How did the Native American culture react to all this?

I would say that modern day Wizarding America would somehow reflect all of that via a loose collection of states. Like Articles of Confederation America. I'd imagine they started becoming Independent in the 19th century, and formed a loose coalition/government by the early 20th century. I'd also think that their national identity is being pretty radically changed by the influx of Muggleborns with their views on their Muggle nationalities.

 

I have written Magical USA not as a single nation, but a lot of magical nations, each usually founded by one family or group of wizards who were unhappy in Europe for a any reason - not pure enough, too hostile to muggleborn, not dark enough, not light enough, and so on. No melting pot effect there. No confederation even. No Revolution - Wizarding Britain and France never tried to rule the colonies, they were glad to be shot of the trouble makers, and magical spain had suffered a lot under the Inquisition, with most magicals heading to Latin America where conquerring the native magical nations kept them occupied.

Since most of the north american continent was settled after the Statute of Secrecy went into effect, the native magical communities survived better than the south and central american ones, even as the non-magical tribes were decimated, and so tribal shamans still play are a force in North American magical politics.

The magical nations are locked in a struggle over a variety of issues ranging from slavery to dark/light disputes and treatment of muggleborns and economics and demographics. It flares up into a hot conflict regularily, usually fanned or manipulated by the tribes and varying other nations who are not involved in that specific hot conflict who want to preent anyone from coming out on top (and then coming after them).

No magical utopia waiting for an excuse to liberate Britain with its awesome technomancy, just a bunch of wizards of all sorts feuding with each other for reasons that sometimes date back to their arrival on the continent, and volatile politics that can change allegiances from day to day, but resist major changes. The only thing they all agree on is that the Statute of Secrecy must be upheld.